A preliminary survey on the occurrence of barbering in laboratory mice in Germany

Although barbering is common in laboratory mice ( Mus musculus), little is known about its effects, both on animal welfare and the research data collected from barbered mice. To gain information on the occurrence of barbering and related risk factors in animal facilities in Germany, we performed an online survey. All the respondents (n = 32 animal facilities) had experienced barbering in their facility. In most cases, less than 10% of the mice were affected, and the age of onset was mostly observed to be 2 to < 6 months. A greater susceptibility was reported in females and in C57BL/6 mice, but this could not be verified as the prevalence of females and the C57BL/6 strain was unknown. One facility reported differences in barbering between commercial animal suppliers. Barbering was also recorded in mice provided with enrichments, such as houses, wood-gnawing blocks, tunnels, running wheels/discs or cage dividers. None of the responding facilities provided swings, structural elements such as an elevated platform or foraging and cognitive enrichment. The questions of whether barbering may have an impact on study results and whether victims of barbering can be used for experiments revealed mixed opinions, most likely due to a lack of data on potential effects. This survey clearly demonstrated barbering to be a widely underestimated problem that is not given enough attention. We suggest that the occurrence of barbering should be systematically documented in every animal facility and reported in research articles, to provide a greater understanding of barbering and its potential effects.

Is a mounted award ceremony in equestrian sport relevant to animal welfare?

Severe accidents befalling both horses and riders have been observed during award ceremonies in equestrian sports. We hypothesised that such ceremonies and subsequent laps of honour pose a significant risk to the well-being of horses, riders and third parties. Tournament riders' opinions were sought and analysis of accidents undertaken via an online questionnaire completed by 700 tournament riders participating in dressage and showjumping in Germany. While 31.3% of the riders reported feeling tense themselves during award ceremonies, greater tension was reported in the warm-up area and throughout the competition itself. In contrast, 48% of horses were at their most tense at award ceremonies and displayed the greatest amount of stress during the lap of honour. Sixty percent of survey participants felt award ceremonies created an increased risk of injury with riders citing stressed horses as being the principal cause. Only risks associated with the warm-up area were noted by a greater proportion of riders (66.6%). The most frequent cause of accidents at award ceremonies was deemed to be kicks. Horse participation at award ceremonies was deemed to be important for spectators and sponsors and, although over half the riders were in favour of compulsory participation with a horse, they expressed the desire for exceptions to be permissible by judge(s). This study supported the hypothesis that mounted award ceremonies have a negative impact on horse welfare.

Deflighting zoo birds and its welfare considerations

For over a century the practice of deflighting has taken place in zoological collections in order to ensure birds remain in open-topped enclosures. Over time, efforts have been made to improve or develop new (surgical) techniques, reduce risk of complications during deflighting and minimise stress and pain during the procedure. However, increased public interest in issues of animal welfare has coincided with a questioning of the practice of removing a birds ability to fly. The ensuing debate, which continues to progress among a variety of differing stakeholders, has led to various legislative adjustments across a number of countries. Despite significant legislation, the dialogue has been both subjective and highly emotive. A plethora of opinions exist as to why deflighting should be outlawed, why it is necessary, or how it has the potential to improve a birds living conditions. However, most are based on assumption or issues unrelated to welfare. To the authors knowledge, to date, no scientific data have been published on the welfare implications of deflighting for the commonly deflighted bird species, such as waterfowl, flamingos (Phoenicopteridae), pelicans (Pelecanidae), storks (Ciconiidae), cranes (Gruidae) and herons (Ardeidae). The aim of this study is to present an overview of the relevance of deflighting to zoo husbandry, the species primarily affected, the techniques currently in use, the legality in differing countries and the extent of scientific knowledge as regards potential ethological and welfare concerns. An urgent need for evidence-based studies is highlighted, to further inform this practice at a species-specific level.

Short communication: Is hair cortisol a potential indicator for stress caused by chronic lameness in dairy cows?

The objective of this study was to evaluate hair cortisol concentration as an indicator for stress caused by chronic lameness in dairy cows. Sixty-eight cows were scored for lameness for 4 consecutive weeks. The hair of the tail switch was clipped at the beginning of the study and regrown hair was clipped after 4 wk. Hair samples were analyzed for cortisol concentration. Animals with 2 consecutive locomotion scores ≥3 or with an overall mean score >1.5 were classified as lame. After pair matching lame and nonlame cows, considering days in milk, lactation number, and milk yield, and excluding cows with less than 20 mg hair sample for analysis, 21 lame and 21 nonlame cows were included in the analysis. The mean hair cortisol concentration in this study was 2.32 ± 0.35 pg/mg (mean ± standard deviation). Cortisol concentration from hair regrown in the study period was 2.38 ± 0.95 and 2.26 ± 1.35 pg/mg for lame and nonlame cows (n = 21), respectively; we found no difference in mean cortisol level of primiparous and multiparous cows. Based on these data, hair cortisol concentration was not a useful indicator to differentiate cows with chronic lameness and healthy cows.

PYY3-36 as an anti-obesity drug target

The neuropeptide Y (NPY)/peptide YY (PYY) system has been implicated in the physiology of obesity for several decades. More recently ignited enormous interest in PYY3-36, an endogenous Y2-receptor agonist, as a promising anti-obesity compound. Despite this interest, there have been remarkably few subsequent reports reproducing or extending the initial findings, while at the same time studies finding no anti-obesity effects have surfaced. Out of 41 different rodent studies conducted (in 16 independent labs worldwide), 33 (83%) were unable to reproduce the reported effects and obtained no change or sometimes increased food intake, despite use of the same experimental conditions (i.e. adaptation protocols, routes of drug administration and doses, rodent strains, diets, drug vendors, light cycles, room temperatures). Among studies by authors in the original study, procedural caveats are reported under which positive effects may be obtained. Currently, data speak against a sustained decrease in food intake, body fat, or body weight gain following PYY3-36 administration and make the previously suggested role of the hypothalamic melanocortin system unlikely as is the existence of PYY deficiency in human obesity. We review the studies that are in the public domain which support or challenge PYY3-36 as a potential anti-obesity target.

Epigallocatechin gallate attenuates diet-induced obesity in mice by decreasing energy absorption and increasing fat oxidation

OBJECTIVE

To examine the antiobesity effect of epigallocatechin gallate (EGCG), a green tea bioactive polyphenol in a mouse model of diet-induced obesity.

METHODS

Obesity was induced in male New Zealand black mice by feeding of a high-fat diet. EGCG purified from green tea (TEAVIGO) was supplemented in the diet (0.5 and 1%). Body composition (quantitative magnetic resonance), food intake, and food digestibility were recorded over a 4-week period. Animals were killed and mRNA levels of uncoupling proteins (UCP1-3), leptin, malic enzyme (ME), stearoyl-CoA desaturase-1 (SCD1), glucokinase (GK), and pyruvate kinase (PK) were analysed in different tissues. Also investigated were acute effects of orally administered EGCG (500 mg/kg) on body temperature, activity (transponders), and energy expenditure (indirect calorimetry).

RESULTS

Dietary supplementation of EGCG resulted in a dose-dependent attenuation of body fat accumulation. Food intake was not affected but faeces energy content was slightly increased by EGCG, indicating a reduced food digestibility and thus reduced long-term energy absorption. Leptin and SCD1 gene expression in white fat was reduced but SCD1 and UCP1 expression in brown fat was not changed. In liver, gene expression of SCD1, ME, and GK was reduced and that of UCP2 increased. Acute oral administration of EGCG over 3 days had no effect on body temperature, activity, and energy expenditure, whereas respiratory quotient during night (activity phase) was decreased, supportive of a decreased lipogenesis and increased fat oxidation.

CONCLUSIONS

Dietary EGCG attenuated diet-induced body fat accretion in mice. EGCG apparently promoted fat oxidation, but its fat-reducing effect could be entirely explained by its effect in reducing diet digestibility.

Physiology: does gut hormone PYY3-36 decrease food intake in rodents?

Batterham et al. report that the gut peptide hormone PYY3-36 decreases food intake and body-weight gain in rodents, a discovery that has been heralded as potentially offering a new therapy for obesity. However, we have been unable to replicate their results. Although the reasons for this discrepancy remain undetermined, an effective anti-obesity drug ultimately must produce its effects across a range of situations. The fact that the findings of Batterham et al. cannot easily be replicated calls into question the potential value of an anti-obesity approach that is based on administration of PYY3-36.

Impaired sodium excretion, decreased glomerular filtration rate and elevated blood pressure in endothelin receptor type B deficient rats

The renal endothelin (ET) system, particularly the ET type B receptor, has been implicated in the regulation of sodium excretion and glomerular filtration rate (GFR). We analyzed kidney morphology and function in a rat strain characterized by complete absence of a functional ETB receptor. Due to Hirschsprung's disease limiting lifetime in these rats, studies were performed in 23-day-old rats. Kidney size and morphology (glomerular and interstitial matrix content, glomerular size and cell density and intrarenal vascular morphology) were normal in ETB-deficient rats. There were also no evidence of altered kidney cell cycle regulation in these rats. GFR was significantly lower, by 72% (P<0.001), in homozygous ETB-deficient rats than in wild-type rats. Fractional sodium excretion was likewise markedly reduced by 84% in homozygous ETB-deficient rats (P<0.001 versus wild-type rats). Treatment with the specific epithelial sodium channel blocker amiloride led to a much higher increase in fractional sodium excretion in ETB-deficient rats (934.2+/-73% in ETB-deficient rats versus 297+/-20% in wild-type rats, expressed as percentage of corresponding placebo treated control; P<0.001). Mean arterial blood pressure was elevated by 7.9 mmHg in homozygous ETB-deficient rats (P<0.05 versus wild-type rats). Our study demonstrates that ETB-deficiency causes early onset kidney dysfunction characterized by a markedly reduced sodium excretion, decreased GFR, and slightly elevated blood pressure. The complete absence of the ETB receptor causes in the kidney--in contrast to the colon--a functional rather than a developmental, neural crest cell dependent disease, since kidney morphology was normal in ETB-deficient rats. The much higher increase in the fractional sodium excretion in ETB-deficient rats after pharmacological blockade of the epithelial sodium channel indicates that the decreased fractional sodium excretion in ETB-deficient rats is most probably due to a lack of the inhibitory property of the ETB receptor on the epithelial sodium channel activity.

ETA receptor blockade induces fibrosis of the clipped kidney in two-kidney-one-clip renovascular hypertensive rats

BACKGROUND

In two kidney-one clip renovascular hypertension (2K1C), blood flow is reduced in the clipped kidney leading to ischaemia. The non-clipped kidney is characterized by increased shear stress. Circulating Ang II is elevated. All these factors are stimuli of the paracrine renal endothelin system. Indeed, we demonstrated an activation of the renal endothelin system in the 2K1C rat model.

METHODS

We analysed the effects of chronic treatment with the ETA receptor antagonist BQ-123 on blood pressure, heart rate, plasma renin activity, and on the progression of glomerulosclerosis, interstitial fibrosis and vascular remodeling in the clipped and non-clipped kidney.

RESULTS

Long-term treatment with BQ-123 led to a fibrotic atrophy of the clipped kidney characterized by a significantly reduced weight of the clipped kidney compared to the clipped kidney of the placebo-treated group. Computer-aided image analysis revealed a markedly enhanced interstitial fibrosis of these clipped kidneys after long-term ETA blockade. The effects of ETA receptor antagonists on the non-clipped kidney were less pronounced. Neither blood pressure nor plasma renin activity were significantly altered by BQ-123 treatment.

CONCLUSIONS

The present study indicates that long-term blockade of the activated endothelin system in the clipped kidney of rats with renovascular hypertension using an ETA receptor antagonist led to a fibrotic atrophy of the clipped kidney.

Regulation of the renal endothelin system in the two-kidney, one clip renal hypertensive rat

Renovascular hypertension in the two-kidney, one clip (2K1C) model is characterized by initially elevated angiotensin-II (A-II) plasma concentrations, caused by ischemia in the clipped kidney and shear stress in the nonclipped kidney. These features are known stimuli of the endothelin (ET) system. The aim of this study was to analyze whether the renal ET system is activated in 2K1C renal hypertension in the rat. Wistar Kyoto rats (9 weeks old) were randomly assigned to four groups. Groups 1 and 3 underwent renal artery clipping, groups 2 and 4 were sham-operated. Groups 1 and 2 were used for analysis at 10 days after clipping, groups 3 and 4 12 weeks after clipping. We measured immunoreactive ET-1 renal tissue concentration as well as the ET(A)- and ET(B)-receptor density and affinity in renal cortex and medulla. We detected an increased immunoreactive ET-1 tissue concentration compared to the sham-operated control in the renal cortex of the nonclipped kidney 10 days (25.6 +/- 12.0 pg/g vs 12.5 +/- 5.0, 1 pg/g; p < 0.05) and in the renal cortex of the clipped kidney 90 days after clipping (92.4 +/- 47 pg/g vs 22.9 +/- 21 pg/g; p < 0.05), An increased ET(A)-receptor density was revealed in the renal medulla of the clipped kidney 10 days (624 +/- 130 fmol/mg vs 276 +/- 68 fmol/mg; p < 0.05) and 90 days (859 +/- 131 fmol/mg vs 493 +/- 93 fmol/mg; p < 0.05) after clipping. There were no differences in ET(B)-receptor density or binding affinity of either ET(A)- or ET(B)-receptors. In the 2K1C rat model of renovascular hypertension the renal ET system is activated. This activation is time-dependent and also dependent on the specific pathophysiological condition (clipped vs nonclipped). Increased ET-1 tissue concentration and upregulation of ET(A)-receptor density might lead to a synergistic activation of the ET system.

Pulmonary fibrosis and chronic lung inflammation in ET-1 transgenic mice

The pulmonary endothelin (ET) system has been implicated in the pathogenesis of chronic lung diseases such as pulmonary hypertension, asthma, chronic obstructive lung disease, idiopathic pulmonary fibrosis, and bronchiolitis obliterans. However, the etiologic role of ET-1 in these diseases has not yet been established. We recently demonstrated that ET-1 transgenic mice, generated using the human prepro-ET-1 expression cassette including the cis-acting transcriptional regulatory elements, had predominant transgene expression in lung, brain, and kidney. We used these mice in the present study to analyze the pathophysiologic consequences of long-term pulmonary overexpression of ET-1. We found that ET-1 overexpression in the lungs did not result in significant pulmonary hypertension, but did result in development of a progressive pulmonary fibrosis and recruitment of inflammatory cells (predominantly CD4-positive cells). Our study provides evidence that a long-term activated pulmonary ET system, without any other stimuli, produces chronic lymphocytic inflammation and lung fibrosis. This suggests that overexpression of ET-1 may be a central event in the pathogenesis of lung diseases associated with fibrosis and chronic inflammation, such as pulmonary fibrosis and bronchiolitis.

Renal endothelin system in polycystic kidney disease

Polycystic kidney disease (PKD) is characterized by interstitial fibrosis and formation of renal cysts. Interestingly, interstitial fibrosis and renal cyst formation were also seen in human endothelin-1 (ET-1) transgenic mice. This study, therefore, analyzes the tissue distribution of ET-1, the tissue concentrations of ET-1, as well as the expression of ET receptor subtypes in the kidneys of a rat model of PKD: Han:SPRD rats. Six-week-old heterozygous (cy/+) and homozygous (cy/cy), as well as 6-mo-old heterozygous (cy/+) Han:SPRD rats and the corresponding age-matched Sprague Dawley littermates (SD) (+/+) were analyzed. Furthermore, the acute effects of the mixed (A/B) endothelin receptor antagonist bosentan on hemodynamic and renal function were investigated in 6-mo-old, conscious, chronically instrumented (cy/+) rats. The kidneys of affected rats showed significantly elevated tissue levels of ET-1 compared with age-matched controls (3.5 +/- 0.3-fold in young cy/cy rats, P < 0.01; 1.4 +/- 0.2-fold in young cy/+ rats, P < 0.01; 6.2 +/- 0.4-fold in old cy/+ rats, P < 0.001) due to a highly increased ET-1 synthesis within the epithelial cells of the cysts. Analyzing tissue sections from patients with typical autosomal dominant PKD demonstrated a high ET-1 expression within the epithelial cells of the cysts as well. Scatchard analysis revealed a markedly decreased ETA and ETB receptor density in all groups of affected rats. The acute blockade of both endothelin receptor subtypes using bosentan in 6-mo-old heterozygous PKD rats led to a significant decrease in mean arterial BP (MAP) (-19.7 +/- 2.1 mmHg, P < 0.05) and GFR (-41 +/- 5%, P < 0.005). Renal blood flow (RBF) was significantly increased (+2.1 +/- 0.5 ml/min, P < 0.05) after bosentan, whereas bosentan had no effect on MAP, GFR, and RBF in age-matched controls. These data show that the paracrine renal endothelin system is activated in PKD and participates in the regulation of MAP, GFR, RBF, and possibly contributes to renal cyst formation and fibrosis.

Apoptosis in kidneys of endothelin-1 transgenic mice

Endothelin-1 (ET-1) transgenic mice are characterized by age-dependent development of renal cysts and renal fibrosis (interstitial fibrosis and glomerulosclerosis), leading to a progressive decrease in glomerular filtration rate. The mechanism causing the loss of functionally and morphologically normal renal tissue is unknown. An imbalance between cell proliferation and apoptosis in the kidneys of ET-1 transgenic mice might contribute to this process. We identified apoptotic cells in kidney sections by in situ end-labeling and by the typical nuclear chromatin morphology after propidium iodide (PI) staining. Cell proliferation was measured by estimating the proliferating cell nuclear antigen (PCNA)-positive cells. The numbers of apoptotic cells were significantly increased (p < 0.001) in the kidneys of 14-month-old ET-1 transgenic mice, whereas cell proliferation was not enhanced. Apoptotic cells were detected in the glomeruli, tubular cells, and renal interstitial cells in ET-1 transgenic mice. In conclusion, apoptotic loss of functional renal tissue appears to be associated with the progression of cyst formation and renal fibrosis. Therefore, an imbalance between cell proliferation and apoptosis could be an important cellular mechanism in ET-1 transgenic mice leading to end-stage kidney disease.

Endothelin-1 transgenic mice develop glomerulosclerosis, interstitial fibrosis, and renal cysts but not hypertension

The human endothelin-1 (ET-1) gene under the control of its natural promoter was transferred into the germline of mice. The transgene was expressed predominantly in the brain, lung, and kidney. Transgene expression was associated with a pathological phenotype manifested by signs such as age-dependent development of renal cysts, interstitial fibrosis of the kidneys, and glomerulosclerosis leading to a progressive decrease in glomerular filtration rate. This pathology developed in spite of only slightly elevated plasma and tissue ET-1 concentrations. Blood pressure was not affected even after the development of an impaired glomerular filtration rate. Therefore, these transgenic lines provide a new blood pressure-independent animal model of ET-1-induced renal pathology leading to renal fibrosis and fatal kidney disease.

The paracrine endothelin system: pathophysiology and implications in clinical medicine

Apart from the initially described vasoconstriction, endothelins have been shown to cause a variety of biological activities in non-vascular tissues. A rapidly growing body of data supports the concept of endothelin as a paracrine acting hormone. In this review, we will discuss the impact of this local endothelin system for various cardiovascular pathophysiological states, especially atherosclerotic vascular disease, restenosis, myocardial infarction, congestive heart failure, and arterial hypertension. In addition, the endothelin system is a modulator of renal function via its binding to abundant receptors in renal tissue and by the ability of renal endothelial and epithelial cells to synthesize and release endothelin. In the kidney, endothelin may function as a paracrine/autocrine factor in the regulation of renal blood flow, glomerular haemodynamics, and sodium and water homeostasis. The renal endothelin system is involved in kidney diseases such as impaired renal function in liver cirrhosis, cyclosporin toxicity, acute renal failure and renal glomerular and interstitial fibrosis. Therapeutic approaches with new orally active endothelin receptor antagonists are also discussed.

Characterization of the renal phenotype of transgenic rats expressing the human endothelin-2 gene

We have previously established a transgenic rat model termed TGR(hET-2)37 overexpressing the human endothelin-2 (ET-2) gene with high renal transgene expression. This renal overexpression is of pathophysiological interest because a long-term activated paracrine renal endothelin system has been implicated in chronic renal failure due to progressive glomerular injury. Therefore, our aim in the present study was to analyze renal transgene expression in detail and address the question of whether transgene expression causes phenotypic and functional changes in the kidney. We used reverse transcription-polymerase chain reaction and in situ hybridization techniques for transgene expression analysis. Tissue ET-2 concentrations were measured with a specific radioimmunoassay. For histological evaluation of renal tissue, all samples were subjected to hematoxylin-eosin and periodic acid-Schiff staining. Renal tissue ET-2 concentrations were significantly increased in TGR(hET-2)37 rats. Using in situ hybridization, we found that the human ET-2 gene was almost exclusively expressed within the glomeruli. The glomerular transgene expression resulted in a significantly increased glomerular injury score and likewise in a significantly increased protein excretion, whereas glomerular filtration rate was not altered. Blood pressure was similar in TGR(hET-2)37 rats and age-matched controls, suggesting that the local changes in the kidney were correlated with paracrine endothelin actions. In conclusion, our study revealed that the major renal expression site of the human ET-2 transgene in TGR(hET-2)37 rats was within the glomeruli and caused the development of glomerulo-sclerosis with significantly increased protein excretion that is independent of blood pressure. We suggest that TGR(hET-2)37 rats are a new monogenetic animal model for study of the paracrine renal endothelin system and its involvement in renal pathophysiology.

Role of the paracrine liver endothelin system in the pathogenesis of CCl4-induced liver injury

This study analyzed if the paracrine liver endothelin system participates in the pathogenesis of CCl4-induced hepatotoxicity. Wistar Kyoto rats were divided into four groups: a bosentan (mixed endothelin ETA and ETB receptor antagonist) treated group with CCl4 intoxication, a vehicle treated group with CCl4 intoxication, a nontreated control group and a bosentan treated control group. Hepatotoxicity was assessed by determination of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) followed by histopathological examinations. Tissue endothelin-1 concentrations and expression of endothelin receptor subtypes were analyzed. The tissue levels of endothelin-1 in the liver of rats with CCl4 intoxication were significantly higher than those in normal rats. Scatchard analysis revealed no differences in the density and binding constant of endothelin ETA and ETB receptor between rats with CCl4 intoxication and controls. Bosentan treatment of rats undergoing CCl4 inhalation resulted in a significant protection against elevation of ALT, AST, LDH and bilirubin. Histopathological examination of live sections for necrotic, swollen and lipid-laden cells revealed findings that were in agreement with the serum enzyme data. In conclusion, this study showed that the paracrine endothelin system is involved in the pathogenesis of CCl4-induced hepatotoxicity and that the blockade of the stimulated liver endothelin systems reduces CCl4-induced liver injury.